This invention relates to a nutritionally based baiting composition and methods for its use in the monitoring and control of termites.
Damage in the United States attributable to subterranean termites is now estimated to be in excess of one billion dollars a year. All wooden or wood-containing structures are potentially affected, including homes, outbuildings, fences, utility poles, railway sleepers, boats, bridges, retaining walls and even living trees. Since their introduction to the United States within the last half-century, Formosan subterranean termites, Coptotermes formosanus, have become one of the most destructive pests in the contiguous United States. Reasons for this include their massive colonies which can contain tens of millions of individuals, their ability to attack several species of living trees, and their high level of reproduction.
The most successful existing methods for control of subterranean termites are preventive rather than remedial. These include barrier treatments to structures and the preemptive treatment of wood materials with chemicals to prevent termite attack. These however have drawbacks. Physical barriers are not compatible for retrofitting on many existing constructions and may not be completely effective, and chemical treatments are only partially effective and last only about five years.
Low toxicity baits utilizing growth regulators have shown success in reducing damage caused by subterranean termites, with hexaflumuron having been particularly effective in suppressing large colonies of C. formosanus. Utilized matrices for the baits have consisted of cardboard, filter paper, pine wood or pure cellulose. These matrices have, however, all suffered from generating less than optimal responses from the termites, which have in varying degree bypassed them in favor of other sources of cellulose such as houses and trees.
While various methodologies and compositions exist for the monitoring and control of termites, there remains a need for the creation of improved tools in this area.
Therefore, it is an object of this invention to provide a bait matrix composition effective as a toxicant delivery system for termites.
Another object is to provide a composition which may be used for the monitoring of termites.
Yet another object is to provide compositions and methods for the effective control of termite populations.
We have discovered that termites may be more effectively monitored and/or controlled through use of a nutritionally-based matrix which works as an attractant and carrier for chemicals which are toxic to termites. A termite matrix containing nutritionally requisite components enhances its usefulness as a bait and an attractant for termites. The termite matrix of this invention is preferred by termites over naturally-occurring foods such as deadwood and trees, wood and cellulose-based products used in human constructions, and other known termite foods such as cardboard. The matrix comprises cellulose as a primary component, since cellulose serves as the basis of the termite""s normal diet. In addition it contains termite-preferred nutrients, i.e., nutrients required for termite growth and development. These nutrients are selected and present in the termite matrix of this invention in such amounts that the termite matrix is preferred by termites over alternate available food sources such as wood and other termite foods known to the art. The invention is premised on applicants"" discovery that termites have the ability to finely discriminate between food sources on the basis of their nutritional value.
In addition to cellulose and water, the termite bait matrix of this invention preferably comprises lipids, vitamins and amino acids required by termites, termite growth factors, as well as feed-conditioning agents which simulate smells and tastes of fermenting food.
Termites for which the termite matrix of this invention is useful include all termite species belonging to the families Rhynotermitidae and Kalotermitidae, preferably Coptoternes formosanus and Reticulitermes flavipes. 
The termite matrix of this invention, also referred to herein as the xe2x80x9cbait matrixxe2x80x9d or xe2x80x9ctermite food,xe2x80x9d may be used to attract termites to the site in which it is placed for purposes of counting and monitoring the size and presence of termite populations.
The matrix may also be used as a highly effective carrier for enhancing the delivery of termite toxins for the purpose of destroying substantial numbers of termites and thus inhibiting termite damage to cellulosic structures such as buildings and trees.
Methods of making termite-preferred matrices of this invention are also provided comprising mixing the various components to form a food, and preferably including the steps of separately mixing autoclavable components (including ethyl alcohol), autoclaving, and adding components which do not tolerate heat such as yeast hydrolysate. The method need not include heat sterilization but preferably does, since water may contain fungal spores which can make the matrix less attractive to termites if they do not discover it immediately after it has been placed in a bait station and the spores have a chance to grow. The method may also include adding termite toxins to the matrix and encasing this matrix in a physical container or a coating material. The container or coating material should be made of a water-retentive, vapor-permeable material.
Methods of killing termites are also provided comprising placing a toxin-containing matrix in a termite habitat upon which the termites will preferentially feed in place of other environmentally-available food sources. The methods preferably also include placing hydrated water-retaining materials (also referred to herein as water-retention agents) within the termite bait matrix or in the area immediately surrounding the termite matrix to provide a degree of humidity to the immediate area which can be detected by termites serve as a second means of attracting them.
Methods of monitoring termite activity in a region are also provided comprising placing a termite bait matrix as described above (referred to herein as a xe2x80x9cbait stationxe2x80x9d) at one or more locations in a region and assessing the presence of termites at the site.
Methods of attracting termites comprising a hydrated water-retention agent in a termite habitat are also provided.
A termite attractant comprising a hydrated water-retention agent contained within a termite-accessible container is also provided. The xe2x80x9ctermite-accessible containerxe2x80x9d refers to a container or coating which retains moisture inside but which termites can enter.
A bait matrix composition for termites has been developed which sufficiently fulfills the nutritional needs of the Formosan and native subterranean termites so as to be preferred by termites to other environmentally available sources of cellulose such as cardboard and southern yellow pine. The matrix can be used in baiting systems to deliver termite toxins to termites. The matrix composition comprises cellulose, water, and termite-preferred nutrients.
The cellulose may be supplied by means of any cellulose-containing material, preferably having 90% to greater than 95% cellulose, so long as it does not include chemicals which are toxic or repellant to termites. Such materials include commercially available cellulose, wood, paper, and cardboard, and are preferably in particulate form for ease of mixing with the other ingredients of the matrix. Sawdust may be from any plant source but is preferably from woods preferred by termites such as maple, birch, sweet gum and related woods. Alternate sources of sawdust, while usable, may contain chemicals in amounts that reduce the utility of such sawdust materials due to either repellant or toxic effects. Preferably, commercially available cellulose powder is used because it is less expensive than sawdust and lacks such chemicals.
Termites prefer foods which are at least partially broken down, as by fermentation, and have pH levels produced by fermentation, i.e., less than about 5, and preferably less than about 4.5. These conditions favor the microorganisms contained in termite guts, including protozoans and bacteria, which break down and digest cellulose. The termite body surface also carries fungal spores which in nature infect the food material and, after a period of time in which fungal growth is established, render it more nutritious. Thus fresh wood material is not a preferred termite food. The termite matrices of this invention possess both appropriate pH and odors indicative of ongoing fermentation processes, both of which serve to attract termites.
The termite matrices of this invention therefore preferably comprise feed-conditioning substances (or breakdown products thereof) which cause the matrices to simulate natural termite foods having a degree of fermentation (infestation with microorganisms and their products), which is attractive to termites. Through use of such conditioning agents, the matrices emit smells attractive to termites. Such conditioning agents include pH-adjusting agents such as hydrochloric, acetic or other acids which are not toxic to termites in the amounts used, present in quantities sufficient to lower the pH of the food to 5 or less. Ethyl alcohol is also used for its ability to dissolve fats and sterols and attract termites. The ethyl alcohol is used in amounts sufficient for its effects to be detected by termites but at a level that does not interfere with the growth of essential microorganisms in the matrix, with this being in an amount ranging from about 0 to about 8 ml/kg of matrix. Preferably, ethyl alcohol is used in amounts between about 0.5 and about 8 ml/kg of matrix. As will be understood by those skilled in the art, if the matrix is heat-sterilized prior to use, the volatile alcohol will evaporate; however, the matrix will contain products resulting from action of the alcohol on other components. Yeast hydrolysate is also a preferred conditioning substance.
If no feed-conditioning substances are used, a period of two or three weeks, depending on the ambient temperature, should be allowed for fermentation to occur to make the matrix attractive to termites.
The degree to which the presence of a particular component causes termites to prefer a food over other foods not containing the component, or containing greater or lesser amounts thereof, may readily be assessed using methods described herein.
The matrix also may comprise vitamins and amino acids characteristic of naturally-occurring termite food or attractive to termites, including vitamins such as riboflavin, D-biotin, choline chloride, vitamin B-12, folic acid, myo-inositol, nicotinamide, calcium pantothenate, pyridoxal hydrochloride, thiamine and ascorbic acid; and amino acids such as L-glutamic acid, L-histidine, L-glutamine, L-alanine, L-lysine, L-isoleucine, L-proline, and L-tyrosine. Vitamin and amino acid-containing materials include yeast and yeast hydrolysate, as well as synthetic solutions that contain these chemicals. Yeast hydrolysate is preferred because of its ability to also act as a food conditioning agent. The vitamins and amino acids may be present in the food at aggregate ratios sufficient to be detectable by termites up to amounts which cause these insects to stop feeding. In the case of yeast hydrolysate, preferred amounts are between about 0.1 g/kg and about 3 g/kg of matrix, more preferably from about 1.0 g/kg of matrix to about 2.0 g/kg of matrix, and most preferably about 1.5 g/kg of matrix. Although it is not necessary that any particular vitamin or amino acid be present in detectable amounts, the aggregate amount of vitamins and amino acids should be present in amounts sufficient to cause the termites to exhibit a preference for foods containing these substances over their ordinary wood diet.
The termite matrix of this invention preferably contains a lipid, preferably a fat or phospholipid which is a source of choline chloride and fatty acids such as linolenic, palmitic, palmetoleic and oleic acids, which are most preferably found in lecithin. Vegetable oils such as corn oil, soybean oil, cotton oil, and other oils known to the art may also be used, as these contain desirably fatty acids such as linolenic acid. If oils such as these not containing choline chloride are used, choline chloride may be added separately to the matrix. The concentration of lipid in the matrix is sufficient to be detectable by termites and less than that causing termite refusal of the food. In the case of lecithin, this amount ranges from about 0.1 g/kg of food to about 12.5 g/kg of matrix, preferably from about 1 g/kg of matrix to about 2 g/kg of matrix, and is most preferably about 1.25 g/kg of matrix.
The matrix may comprise a growth factor required for termite growth, reproduction, and/or chitin formation. Preferably, the growth factor is ergosterol, a sterol produced by fungal infection of food materials by spores carried on the termite body, which emits a characteristic smell attractive to termites. Other useful growth factors include fatty acids and amino acids, such as the nutrients described above, and preferably linolenic acid. The growth factor should be present in an amount sufficient to be detectable by termites, but not so great as to be toxic or cause termites to refuse to feed on the matrix. In the case of ergosterol, the ratio of ergosterol to food is preferably between about 0 and about 4.5 g/kg of matrix, more preferably from about 0.2 g/kg of matrix to about 1.0 g/kg of matrix, and most preferably is about 0.45 g/kg of matrix.
The matrix may further comprise salts useful to termites such as calcium chloride, cobalt chloride, ferric chloride, zinc chloride, potassium phosphate, sodium phosphate, magnesium sulfate, copper sulfate, and manganese sulfate. Amounts of salts may vary. Salts are preferably present in the food in amounts sufficient to that the aggregate ratio of salts to matrix is sufficient to cause the termites to exhibit a preference for the matrix. A good source of such salts is commercially available bottled drinking or spring water, preferably below a pH of about 6, which can be used to provide the requisite moisture for the matrix. Barbe""s(copyright) water, available from Barbe""s Dairy Company, West Wego, La., is a preferred water to supply salts to the matrix.
Subterranean termites prefer moist foods. To be more attractive than other available foods in the environment, the matrix of this invention must be moist. Enough water should be used to allow mixing of the matrix material, and/or completely hydrate the particulate or solid cellulose materials and to provide excess water to maintain a humid environment. In general about three-fourths by weight of the matrix should be water, but this may vary with the water content ranging from about 50% to about 90% by weight of the composition.
To ensure an acceptable moisture level in the matrix material as well as to serve as another means for termite attraction, a water-retention agent capable of absorbing water and releasing it slowly to the environment is used. Examples of such materials include agar and polyacrylamide, but may include any substance not otherwise possessing a repellant effect. Examples of preferred usable materials include the polyacrylamides such as Terrawet(copyright) T-400, Terrawet Company, San Diego, Calif., used in greenhouses which can absorb and retain up to a thousand times their own weight in water. These materials should be hydrated, preferably fully-hydrated, with the addition of at least three times their weight in water. The hydrated water-retaining materials may be mixed in with the matrix.
The inventors have discovered that termites are attracted during their foraging to high humidity conditions, preferably at least about 80% humidity, and more preferably at least about 90% humidity. Thus, moisture-retaining material as described above is preferably placed in the immediate environment of the bait matrix to provide a humidity readily detectable by and attractive to termites. In a preferred embodiment in which a polyacrylamide such as Terrawet(copyright) 400 is used as the water-retaining agent, it may be placed in the area of a termite bait or monitoring station at an application rate effective for eliciting an attractive response, which for a polyacrylamide ranges from about 1 g to about 10 g (dry weight) per square foot. The hydrated polyacrylamide, preferably hydrated to a water:polymer weight ratio of at least about 30:1, can be injected into the soil around the bait station by pressure using commercially available injectors, preferably to a radius around the bait matrix of at least about 2.5 cm. Other water-retaining agents as described above can alternatively be used, adjusting ratios to achieve 80% to 90% humidity as will be readily apparent to those skilled in the art.
The termite matrix of this invention may be used to attract termites to its immediate environment for purposes of monitoring the size and presence of termite populations, e.g., by observing termites and counting or otherwise estimating the number of termites present by measuring the consumption of matrix. Typical monitoring strategies utilize approximately one bait station per 10-15 linear feet. The significantly faster response of termites to the bait matrix of this invention compared to the pine wood conventionally used results in enhanced monitoring efficacy, and means that shorter periods between inspections may be required than is the case with pine wood. Additionally, the bait matrix of this invention may be used in combination with a preferred wood or yellow pine wood to extend the period of termite activity at the monitoring site.
The termite matrix of this invention may also be used as a carrier for any conventional termite toxin such as hexaflumuron, imidacloprid and 5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]- 4-[(3-fluoromethyl)-sulfonyl]-1-H-pyrazole-3-carbonitride (referred to herein as xe2x80x9cfipronilxe2x80x9d) of Chem Service, Inc., West Chester, Pa. Other bioactive compounds not conventionally recognized as termite toxicants may also be used as termiticides. These include streptomycin sulfate, rifampicin, albendazole, neomycin sulfate, sorbic acid, and commercially available antimycotics such as antibiotic antimycotic available from Sigma Company, St. Louis, Mo. For biocidal efficacy, toxins must be present in amounts less than those detectable by termites, with this amount typically being less than about 1000 ppm for hexaflumuron, imidacloprid, and fipronil and other antimicrobials. Due to the high rate of consumption induced by the feed matrix of the instant invention, satisfactory kill of termites can be achieved with toxicant concentrations well below the rejection threshold. Useful amounts typically range from about 1 ppm to about 200 ppm of the bait composition. Preferred concentrations, while being readily determinable by conventional methods, are typically about 25 to about 50 ppm for hexaflumuron, about 1 to about 5 ppm for imidacloprid and fipronil, and about 5 to about 12.5 ppm for other antimicrobials.
The matrix materials of this invention, with or without toxins, may be encased in materials or containers which are water-retentive such that they substantially prevent evaporation of the moisture in the food, but which are vapor-permeable to a degree sufficient to allow termites to detect odors coming from the matrix. Suitable materials may be readily determined by the practicing artisan and include hard waxes with low melting points such as paraffin or beeswax in which pieces of the matrix material can be dipped or which can be otherwise coated on the matrix, and moldable polymers such as styrofoam, and polyurethane foams such as Great Stuff(copyright), Flexible Products Company, Joliet, Ill. Fibrous casing tubes for sausages such as those available from L.E.M. Products, Inc., Miamitown, Ohio, which consists of cotton fibers coated with wax, turned inside out so as not to present the wax surface to the termites, are also preferred materials to be used for containers for the matrices of this invention.